//      eje_mult_3.c
//
//      Copyright 2011 Angel <angel aka Cesar_Biker>
//
//      This program is free software; you can redistribute it and/or modify
//      it under the terms of the GNU General Public License as published by
//      the Free Software Foundation; either version 2 of the License, or
//      (at your option) any later version.
//
//      This program is distributed in the hope that it will be useful,
//      but WITHOUT ANY WARRANTY; without even the implied warranty of
//      MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
//      GNU General Public License for more details.
//
//      You should have received a copy of the GNU General Public License
//      along with this program; if not, write to the Free Software
//      Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
//      MA 02110-1301, USA.


#include <stdio.h>
#include <stdlib.h>

int main(int argc, char **argv)
{
    int numero;
    int l_numeros[81];
    int numeros;
    int i = 0;
    int j;

    while((numero = getchar()) != '\n')
    {
        numeros = 0;
        i = 0;
        j = 0;
        for(; numero != '\n';i++)
        {
            l_numeros[i] = (numero - 48);
            numero = getchar();
        }

        for(j = 0;j < i;j++)
            numeros += l_numeros[j];

        if((numeros % 3) == 0)
            printf("Ok\n");
        else
            printf("No\n");
        //printf("%d",numeros);
    }
    return 0;
}